Synthetic Approach to Analogues of the Original Structure of Sclerophytin A

2002 ◽  
Vol 67 (19) ◽  
pp. 6848-6851 ◽  
Author(s):  
Michael E. Jung ◽  
Joseph Pontillo
Keyword(s):  
Original Structure ◽  
Synthetic Approach ◽  
Sclerophytin A

scholarly journals Total Syntheses of the C19 Diterpenoid Alkaloids (–)-Talatisamine, (–)-Liljestrandisine, and (–)-Liljestrandinine by a Fragment Coupling Approach

2021 ◽  
Author(s):  
Alice Wong ◽  
Nicholas Fastuca ◽  
Victor Mak ◽  
Jeff Kerkovius ◽  
Susan Stevenson ◽  
...  
Keyword(s):  
Original Structure ◽  
Synthetic Approach ◽  
Diterpenoid Alkaloids ◽  
Total Syntheses ◽  
Pinacol Rearrangement ◽  
Coupling Approach ◽  
Structure Assignment

<p>The C19 aconitine-type diterpenoid alkaloids (–)-talatisamine, (–)-liljestrandisine, and (–)-liljestrandinine have been prepared in 31, 30, and 33 steps, respectively, from phenol. The synthetic approach features a 1,2-addition/semi-pinacol rearrangement as the key fragment coupling tactic. These efforts have also resulted in a correction to the original structure assignment of (–)-liljestrandisine.</p>

Synthetic approach to potential precursors of sclerophytin A

Tetrahedron ◽  
2003 ◽  
Vol 59 (15) ◽  
pp. 2729-2736 ◽  
Author(s):  
Michael E Jung ◽  
Joseph Pontillo
Keyword(s):  
Synthetic Approach ◽  
Sclerophytin A

New Insights into the Nature of the Band Gap of CuGeO3 Nanoparticles: Synthesis, Electronic Structure, and Optical and Photocatalytic Properties

2019 ◽  
Author(s):  
Victor Y. Suzuki ◽  
Luís Henrique Cardozo Amorin ◽  
Natália H. de Paula ◽  
Anderson R. Albuquerque ◽  
Julio Ricardo Sambrano ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Material Design ◽  
Photocatalytic Properties ◽  
Critical Parameters ◽  
Synthetic Approach ◽  
Microwave Assisted ◽  
Theoretical Approaches ◽  
Nanoparticles Synthesis ◽  
First Time

<p>We report, for the first time, new insights into the nature of the band gap of <a>CuGeO<sub>3</sub> </a>(CGO) nanocrystals synthesized from a microwave-assisted hydrothermal method in the presence of citrate. To the best of our knowledge, this synthetic approach has the shortest reaction time and it works at the lowest temperatures reported in the literature for the preparation of these materials. The influence of the surfactant on the structural, electronic, optical, and photocatalytic properties of CGO nanocrystals is discussed by a combination of experimental and theoretical approaches, and that results elucidates the nature of the band gap of synthetized CGO nanocrystals. We believe that this particular strategy is one of the most critical parameters for the development of innovative applications and that result could shed some light on the emerging material design with entirely new properties.</p> <p><b> </b></p>

General Cyclopropane Assembly via Enantioselective Redox-Active Carbene Transfer to Aliphatic Olefins

2018 ◽  
Author(s):  
Marc Montesinos-Magraner ◽  
Matteo Costantini ◽  
Rodrigo Ramirez-Contreras ◽  
Michael E. Muratore ◽  
Magnus J. Johansson ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Chemical Space ◽  
Synthetic Approach ◽  
Asymmetric Cyclopropanation ◽  
Redox Active ◽  
Wide Range ◽  
Leaving Group ◽  
Stereoelectronic Properties ◽  
Carbene Transfer

Asymmetric cyclopropane synthesis currently requires bespoke strategies, methods, substrates and reagents, even when targeting similar compounds. This limits the speed and chemical space available for discovery campaigns. Here we introduce a practical and versatile diazocompound, and we demonstrate its performance in the first unified asymmetric synthesis of functionalized cyclopropanes. We found that the redox-active leaving group in this reagent enhances the reactivity and selectivity of geminal carbene transfer. This effect enabled the asymmetric cyclopropanation of a wide range of olefins including unactivated aliphatic alkenes, enabling the 3-step total synthesis of (–)-dictyopterene A. This unified synthetic approach delivers high enantioselectivities that are independent of the stereoelectronic properties of the functional groups transferred. Our results demonstrate that orthogonally-differentiated diazocompounds are viable and advantageous equivalents of single-carbon chirons<i>.</i>

Reed (Phragmites australis agg.) dominated plant communities in the Lower Volga Valley

2015 ◽  
pp. 26-37
Author(s):  
V. B. Golub ◽  
V. V. Bondareva ◽  
A. N. Sorokin ◽  
L. F. Nikolaychuk
Keyword(s):  
Expert System ◽  
Phragmites Australis ◽  
Plant Communities ◽  
Floristic Composition ◽  
Original Data ◽  
Optimal Level ◽  
Point Of View ◽  
Original Structure ◽  
Volga River ◽  
Lower Volga

Plant communities with reed domination (Phragmites australis agg.) occupy the large areas in the Lower Volga Valley and especially in the river delta. We have set the task to reveal the diversity of these communities in the Lower Volga Valley. For this purpose, we applied the database that is registered in the Global Index of Vegetation-Plot Databases (GIVD) under the EU-RU–002 index (http://www.givd.info/) and includes 14871 relevés made during the period from 1924 to 2013. Communities with the dominance of reed were defined as such, if the coverage of this plant was more than 50 %. We have found 375 such relevés in the database. At first, one basal community, 3 associations and 3 subassociations with domination of Phragmites australis agg. were distinguished in the Lower Volga Valley. All processing and analysis of relevés were performed using the software package JUICE 7.0. (Tichý, 2002). The «Cocktail» method was applied to establish the sociological groups that indicate environmental conditions (Bruelheide, 2000). The expert system for selection from the database of relevés by means of these groups was created. It is allowed us to ascribe relevés to earlier distinguished associations, subassociations and basal community. 171 relevés have been identified by the expert system and they were assigned to association, subassociation or the basal community. 204 relevés were not referred to any association, subassociation or the basal community. We wanted to answer the question: are there among these 204 relevés, which could be interpreted as the new syntaxa, giving them the proper ecological characteristics? For this purpose, the cluster analysis of 204 relevés has been carried out. The optimal level of clustering was determined by calculating the index of “crispness of classification” (Botta-Dukát et al., 2005). The greatest “crispness of classification” was reached at allocation of 13 clusters. Consideration of the floristic composition of allocated groups had shown that 11 of them were the transitional plant communities among the earlier established syntaxa. Only two clusters were differed in rather original structure that we could explain by the influence of environment factors. We have identified them as new associations Rubio tataricae-Phragmitetum australis and Cynancho acuti-Phragmitetum australis. All associations with the dominance of Phragmites australis agg. distinguished in the Lower Volga Valley were included in the alliance Phragmition communis Koch 1926, order Phragmitetalia communis Koch 1926. In literary sources from the ecological point of view these syntaxa are defined as the wetland communities, which are closely linked to water bodies (Šumberová et al., 2011; Ermakov, 2012). However, in many cases this definition does not correspond to the ecology of plant communities with the dominance of reed in the lower reaches of the Volga River. Ecotops of these communities are flooded for up to 2–3 months in a year and then they dry out. In the autumn, the ground water level can drop to a depth of one meter (Golub et al., 2011). The plant satellites of the reed here are often mesophytic plants such as Rubus caesius, Calamagrostis epigeios, Phalaris arundinacea, Rubia tatarica, Althaea officinalis, and Rumex stenophyllus. Therefore, the inclusion of phytocoenosises with domination of the reed in the lower reaches of the Volga River in the alliance Phragmition communis is rather relative. A correct placement of these plant communities in the system of vegetation syntaxa of the arid areas can be made only if it is based on original data obtained from much bigger territory than the Lower Volga Valley. In future geobotanical studies, it is desirable to divide the aggregation of Phragmites australis agg. into smaller species taxa.

Diseases Prevention by Water Defluoridation Using Hydrotalcites as Decontaminant Materials

2017 ◽  
Vol 68 (1) ◽  
pp. 168-171 ◽  
Author(s):  
Letitia Doina Duceac ◽  
Cristina Elena Dobre ◽  
Ioana Pavaleanu ◽  
Gabriela Calin ◽  
Simona Nichitus ◽  
...  
Keyword(s):  
Dental Fluorosis ◽  
Precipitation Method ◽  
Original Structure ◽  
Fluoride Removal ◽  
Major Goal ◽  
Bone Stiffness ◽  
Morphological Aspects ◽  
Adsorption Capacities ◽  
Interlayer Structure ◽  
Co Precipitation

Preventing diseases is deemed to be the major goal of our century especially when an excessive fluoride in drinking water can cause dental fluorosis, bone stiffness, rheumatism and skeletal fluorosis. Fluoride uptake from groundwater implies a worldwide multidisciplinary effort in order to develop renewable, cheap, human friendly materials. Among other materials, hydrotalcites could be good candidates for an efficient fluoride removal from water due to their adsorption, anion exchange and reconstruction properties. These nanostructured materials were synthesized using co-precipitation method in controlled conditions. Presence of anions in the interlayer structure and morphological aspects were performed by FTIR and SEM techniques. Thermal treatment of hydrotalcites showed good adsorption capacities for water defluoridation mostly due to their tendency to restore the original structure.

Green Synthesized Nanomaterials as Theranostic Platforms for Cancer Treatment: Principles, Challenges and the Road Ahead

2019 ◽  
Vol 26 (8) ◽  
pp. 1311-1327 ◽  
Author(s):  
Pala Rajasekharreddy ◽  
Chao Huang ◽  
Siddhardha Busi ◽  
Jobina Rajkumari ◽  
Ming-Hong Tai ◽  
...  
Keyword(s):  
Nanoparticle Synthesis ◽  
Research Field ◽  
Synthesis Methods ◽  
Synthetic Approach ◽  
Future Directions ◽  
The Road ◽  
New Methods ◽  
Recent Developments ◽  
Theranostic Applications ◽  
Insight Into

With the emergence of nanotechnology, new methods have been developed for engineering various nanoparticles for biomedical applications. Nanotheranostics is a burgeoning research field with tremendous prospects for the improvement of diagnosis and treatment of various cancers. However, the development of biocompatible and efficient drug/gene delivery theranostic systems still remains a challenge. Green synthetic approach of nanoparticles with low capital and operating expenses, reduced environmental pollution and better biocompatibility and stability is a latest and novel field, which is advantageous over chemical or physical nanoparticle synthesis methods. In this article, we summarize the recent research progresses related to green synthesized nanoparticles for cancer theranostic applications, and we also conclude with a look at the current challenges and insight into the future directions based on recent developments in these areas.

Click Reactions in Chemistry of Triterpenes - Advances Towards Development of Potential Therapeutics

2018 ◽  
Vol 25 (5) ◽  
pp. 636-658 ◽  
Author(s):  
Jan Pokorny ◽  
Lucie Borkova ◽  
Milan Urban
Keyword(s):  
Biological Activities ◽  
Synthetic Approach ◽  
Clinical Use ◽  
New Approach ◽  
Click Reactions ◽  
Drug Candidates ◽  
The Past ◽  
Low Toxicity ◽  
New Compounds ◽  
Potential Therapeutics

Triterpenoids are natural compounds with a large variety of biological activities such as anticancer, antiviral, antibacterial, antifungal, antiparazitic, antiinflammatory and others. Despite their low toxicity and simple availability from the natural resources, their clinical use is still severely limited by their higher IC50 and worse pharmacological properties than in the currently used therapeutics. This fact encouraged a number of researchers to develop new terpenic derivatives more suitable for the potential clinical use. This review summarizes a new approach to improve both, the activity and ADME-Tox properties by connecting active terpenes to another modifying molecules using click reactions. Within the past few years, this synthetic approach was well explored yielding a lot of great improvements of the parent compounds along with some less successful attempts. A large quantity of the new compounds presented here are superior in both activity and ADME-Tox properties to their parents. This review should serve the researchers who need to promote their hit triterpenic structures towards their clinical use and it is intended as a guide for the chemical synthesis of better drug candidates.

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